It will be appreciated that there are many electronic and/or electromagnetic devices for detecting or sensing the presence of objects moving along a predetermined path but these former arrangements are possessed of various shortcomings which restrict their usage only to ideally controlled environmental surroundings. However, in railway and mass and/or rapid transit operations, the sensors or detectors must be capable of properly functioning under extreme vibration, varying climatic conditions, drastic electrical effects, and vigorous physical abuse. Further, in various applications, such as vehicle detection, check-in/check-out operation, inductive train stop, and cut-in train control, it is mandatory that the apparatus functions in a fail-safe manner. In addition, it is necessary that the detecting arrangement not only must be rugged in construction but also must be simple, economical, and lightweight yet reliable in operation.